Update devDependencies. (#27764)

Author: XhmikosR

_config.yml

@@ -56,8 +56,8 @@ cdn:
   js_bundle_hash:   "sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy"
   jquery:           "https://code.jquery.com/jquery-3.3.1.slim.min.js"
   jquery_hash:      "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo"
-  popper:           "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.5/umd/popper.min.js"
-  popper_hash:      "sha384-a3GqK/TQoh+gPFAiesulJK7xiYNo3loQBWP1a68OkSUM5SqmmQxhzdMUGuNlAw3r"
+  popper:           "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.6/umd/popper.min.js"
+  popper_hash:      "sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut"
 
 toc:
   min_level:        2